The overall objective of the Neuroimaging Core is to provide the HNRC and associated investigators unique, non-invasive methods for: 1) in vivo detection and measurement of HIV-related brain damage, 2) elucidation of pathological mechanisms that give rise to this damage, 3) further investigation of the functional consequences using fMRI, and 4) identification of neural correlates of treatment success and failure. In the current funding period, the Core has (1) supported 21 extramurally funded projects, resulting in, for example, findings discriminating HIV-related from age-related white matter abnormalities, convergent and divergent patterns of brain structural abnormalities in HIV infection and methamphetamine dependence, fMRI evidence of compensatory activation in response to neural dysfunction in HIV, and MR spectroscopy detection of potential central neuronal injury related to antiretroviral treatment;(2) trained 12 postdoctoral, graduate, and undergraduate trainees in neuroimaging research;and (3) provided consultation and assistance to national and international collaborators in two multicenter trials. Our aims in the proposed renewal period are to accomplish the following: a) acquisition of high-resolution structural images and tissue metabolite measures to evaluate late-stage HIV disease;b) application of morphometry techniques, designed specifically for this population, to measure tissue loss and damage;c) support of other HNRC, national, and international neuroimaging investigations with consultation and training;d) contribution of data and expertise for the development of improved automated morphometry tools;and e) education of the HIV research community regarding promising new imaging methods for NeuroAIDS research. Additionally, during the next funding period specific new method developmental studies will be initiated to define the histological characteristics of visible abnormalities on in vivo MRI in individual cases that come to autopsy, employing novel high-resolution histological and imaging methods to understand of the meaning of MRI-visible abnormalities This Core will enhance HNRC transdisciplinary aims through close collaboration with other HNRC Cores, particularly the Neuromedical, Neurobehavioral, and Neurobiology. These broad-ranging functions of the Neuroimaging Core ensure state of the art neuroimaging support for HNRC-associated studies, close integration between the interdisciplinary HNRC investigative team, and, as appropriate, linkage to the larger national and international neuroimaging community.